1. Field of the Invention
The present invention relates to an adapter for use in puncture (or centesis), and more particularly to an adapter which is attached to a probe and guides a puncture needle.
2. Description of Related Art
An adapter for use in puncture (which will be hereinafter referred to as a “puncture adapter”) is used for performing puncture with respect to a target tissue through a surface of a living body while an ultrasonic image of the target tissue within the living body is observed. Generally, such an adapter is detachably mounted onto a probe and holds and guides a puncture needle. Japanese Patent Laid-Open Publications Nos. Sho 60-92747, Hei 4-303440, and 2001-120553 describe a puncture adapter which guides a puncture needle such that a puncture route of the puncture needle coincides with (or is included in) a scan plane which is formed by scanning of an ultrasonic beam. More specifically, a guide unit for the puncture needle is provided above one end side of the scan plane and the puncture needle is guided therefrom in the diagonal direction so as to advance on the scan plane. This guiding structure allows an operator to observe, on a tomographic image corresponding to the scan plane, how the puncture needle is gradually introduced, thereby assisting the operator to perform puncture with respect to the target tissue at the optimal angle or in the optimal direction.
With the conventional puncture system described above, while it is possible to observe the structure of a tissue located on the scan plane including the puncture route, the tissue before and behind the scan plane cannot be observed. For example, the carotid artery and jugular vein run adjacent to each other in the neck portion of a human body. When one wishes to insert a puncture needle into the jugular vein in the diagonal direction with respect to the axial direction of the jugular vein in order to insert a catheter, it is desired that the puncture is performed while both the carotid artery and the adjacent jugular vein are being observed simultaneously on a tomographic image. To do so, it may be possible to fix the guide unit for the puncture needle above the region anterior or posterior of the scan plane and guide the puncture needle therefrom in the diagonal direction, i.e. in the direction in which the puncture needle penetrates the scan plane diagonally. However, while such a structure allows observation of a transverse section of each blood vessel on the tomographic image, this structure has a disadvantage that the position of the tip of the puncture needle cannot be recognized on the image until the tip reaches the scan plane. In other words, it is not possible to confirm the route through which the puncture needle is being introduced within the living body on the tomographic image. This problem similarly exists in cases where puncture is performed with respect to portions other than the neck.